In recent years, a technology for realizing a replication system by applying a transaction log has been proposed. With a transaction log, it is possible to realize high-speed operation while maintaining the permanence of database changes by recording a history of changes implemented to a database in an area different from a recording area of the database. A history of all updates is stored in a transaction log, thus it is possible to reconstruct all updates of the database as long as the transaction log is stored.
Proposed as a synchronization method of data with a transaction log is a method for completing a synchronization process of data between a master node and slave nodes when a transfer source node (master node) starts keeping a transaction log in a recording area, transfers the same transaction log to all the other nodes existing in a replication system, the transfer destination nodes (slave nodes) notify the master node of completion after completing the receipt of the transaction log, the master node receives the notifications of completion from all the slave nodes, and a recording process in its own recording area ends (see Japanese Patent Application Laid-Open No. 2006-293910, for example). In this method, it is possible to quickly execute a search process since it is unnecessary to inquire again of the master node about the latest information when the slave node makes a search.
However, the above data synchronization method has a problem that whenever a database (a “database” may hereinafter be referred to as “DB”) of a master node is changed, deleted and updated (“change, delete, and update” may hereinafter be referred to as “update”), a synchronization process with all replica DBs (“databases of transfer destination nodes” in Patent Document 1) is performed so that if a synchronization process of any replica DB takes time because of a failure in any one of any node and a communication path thereof, it takes time to complete the synchronization process and the performance of an entire system decreases.
A main object of the present invention is to provide a method and system for managing the replication of data, which improve the above problem and encourage an improvement in the performance of the entire system while maintaining synchronization of data sequentially updated and enabling a speedy search through the data.